排序方式: 共有19条查询结果,搜索用时 15 毫秒
1.
S. Boichot M. Fromm C. Savall F. Palmino J. C. Labrune A. Chambaudet 《Radiation measurements》1999,31(1-6):233-236
For the observation of nuclear tracks, Atomic Force Microscopy (AFM) is a useful technique. In our study, we have irradiated a muscovite mica sample using 600 keV oxygen ions. This ion's energy is well below the detection threshold predicted by the existing models. The samples were visualized at high resolution with an AFM device. Before chemical etching no tracks were visualized on the surface at an atomic level. However, defects must have been initiated because tracks became observable after a brief etching time. Our results confirm that the detection threshold is influenced by the observation tool. In this article we provide information concerning the “observability” and “etchability” of latent tracks. 相似文献
2.
Two-layer monoclinic(2 M) muscovite mica sheets with a thickness of 12 μm are irradiated with Sn ions at room temperature with electronic energy loss( dE/dx)_e of 14.7 keV/nm. The ion fluence is varied between 1×10~(11) and1×10~(13) ions/cm~2. Structural transition in irradiated mica is investigated by x-ray diffraction(XRD). The main diffraction peaks shift to the high angles, and the inter-planar distance decreases due to swift heavy ion(SHI) irradiation. Dehydration takes place in mica during SHI irradiation and mica with one-layer monoclinic(1 M) structure is thought to be generated in 2 M mica after SHI irradiation. In addition, micro stress and damage cross section in irradiated mica are analyzed according to XRD data. High resolution transmission electron microscopy(HRTEM) is used on the irradiated mica to obtain the detailed information about the latent tracks and structural modifications directly. The latent track in mica presents an amorphous zone surrounded by strain contrast shell, which is associated with the residual stress in irradiated mica. 相似文献
3.
Dina M. Bower 《Journal of Raman spectroscopy : JRS》2011,42(8):1626-1633
Laminated sandstones from the 2.9 Ga Pongola Supergroup, South Africa, were characterized using micro‐Raman spectral imaging to elucidate the origin of the mineral components. These sandstones were formed in a paleoenvironment conducive to sustaining life and contain compelling features reminiscent of ancient microbial mat remains. Most sedimentary rocks of this age have been altered over time through metamorphism and weathering, obscuring any original biologic or mineralogic signatures. Therefore, determination of the exact formation mechanism for biologically associated features is often precluded, resulting in large gaps in our understanding of early life and Earth's early habitable environments. The results of the Raman analyses show that the parallel to bedding laminations in these rocks consist of elongated muscovite grains that are intimately associated with anatase, rutile, goethite, and graphitic carbon. The morphology, orientation, and intimate associations of the component mineral assemblage in the laminations suggest that physiochemical events, such as weathering, low‐grade metamorphism, or hydrothermal fluids, were also key in their formation and influenced their geochemical makeup. Given the complicated histories of ancient sedimentary rocks, the use of techniques such as micro‐Raman spectroscopy is crucial in determining the origins of sedimentary structures that might otherwise be misinterpreted. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
4.
采用液相还原法制备了纳米镍掺杂白云母微粉(Muscovite,简记为Mu)的复合粉体Mu/Ni,表征了复合粉体的微观形貌、晶体结构和元素组成.利用环-块摩擦磨损试验机考察并比较了Mu/Ni和Mu作为锂基润滑脂添加剂的摩擦学性能,对磨损表面的粗糙度、二维和三维形貌以及元素组成进行了分析,探讨了Mu/Ni复合粉体的减摩抗磨机理.结果表明:复合粉体中纳米镍粒子均匀负载在白云母微粉表面,Mu/Ni和Mu作为添加剂均能有效提高锂基润滑脂的摩擦学性能,且Mu/Ni相比于Mu表现出更好的减摩抗磨性能,摩擦系数较锂基润滑脂降低了67.9%.Mu/Ni优良的摩擦学性能与白云母的层状结构及磨损表面生成的含有O、Fe、Si、Al和Ni等元素的润滑膜有关. 相似文献
5.
M. Ciubotariu A. Danis L. Staicu E. Iancu G. Dumitrescu M. Cucu 《Radiation measurements》1997,28(1-6):353-356
Using animals a study on the internal contamination by U ingestion is presented. Two rats of Wistar-London breed were contaminated at once and after different time intervals, 3 days and 10 days respectively, they were sacrified. Uranium biodistribution in the vital organs as well as the uranium retention and elimination was investigated using the fission track method. For the two contaminated subjects a comparison between obtained quantitative results is given. 相似文献
6.
7.
Specimens of muscovite from Siluro-Devonian Appalachian granites of the Gander zone in New Brunswick were studied by 57Fe Mössbauer spectroscopy, microprobe analysis and X-ray powder diffractometry. Chemical compositions, corresponding structural formulae and powder patterns indicate that they are dioctahedral true micas of 2M1 polytype. Mössbauer spectroscopy shows that these muscovites fall into two groups having distinct spectra, despite an absence of systematic differences in their chemical compositions, X-ray patterns, unit-cell parameters, and Fe3+/Fetotal ratios. In the first group, two distinct and well-resolved viFe2+ spectral contributions occur whereas, in the second group, a single but broader viFe2+ contribution occurs. All spectra from both groups have viFe3+ contributions. These observations are confirmed by quadrupole splitting distribution (QSD) analyses of the spectra. Spectra from the first group clearly show a bimodal distribution of quadrupole splittings for Fe2+, with a dominant contribution at ~3.0 mm/s and a minor one at ~2.1 mm/s. In the second group, the spectra show a broad unimodal distribution of QSDs for Fe2+. We attribute the 3.0 and 2.1 mm/s QSD components to Fe2+ in cis and trans octahedral sites, respectively. Muscovites from our second group may have Fe2+ in both cis and trans sites but these cannot be resolved, as is usually the case, for example, with trioctahedral micas. In group one, cis/trans populations provide measures of the degree of cation order and of the density of vacancies on the cis sites. Simple models based on average unit cell site dimensions are found not to hold. Local effects seem to dominate, with Fe2+ showing no systematic preference for cis or trans sites. 相似文献
8.
I. L. Lapides 《Journal of Thermal Analysis and Calorimetry》1994,42(1):197-206
Several isomorphic groups of micas: Muscovite-Phengite-Muscovite-Li-Muscovite; Biotite-Zinnwaldite-Lepidolite and Biotite-Phlogopite
were investigated by DTA, TG and DTG. Octehedral vacancies and the sites of octahedral cationic occupancy were determined
from IR-spectra of the hydroxyls. The influence of a composition and fine structure of the micas on the shape of the thermal
curves was discussed. A one to one correspondence between the isomorphic series members and individual thermal curves makes
it possible to determine the chemical composition of a mica sample. The combination of thermal and IR-spectra of hydroxyl
analyses permits to link the Order-Disorder data with thermal properties of mica.
Dedicated to Professor Lisa Heller-Kallai on the occasion of her 65th birthday 相似文献
9.
Ultrahigh specific surface area muscovite with different ions at the surface (Li+, Na+, K+, Rb+, Cs+, Ca2+, Sr2+, Ba2+, Cu2+) was treated with aqueous solutions of low molecular weight crown ethers and polymers with crown ether substituents. The adsorption was assessed by UV analysis of the supernatant solution, and with TGA and IR spectroscopy of the mica solids. In contrast to other layered silicates, the low molecular weight crown ethers show no affinity to any of the muscovite surfaces. The polymers can adsorb, however, depending on the type of surface cation. The results indicate that at least some of the crown ether moieties are complexed to surface cations and that the diameter of the ions at the surface plays an important role in the adsorption process. 相似文献
10.